There was a reddit experiment a few years back, SubredditSimulator, that was a scaled version of what you described. It was obviously more surreal and funny tha

There was a reddit experiment a few years back, SubredditSimulator, that was a scaled version of what you described. It was obviously more surreal and funny than accurate. There were users trained off of popular subreddits, and they just ran with threads and comments being created purely from the data.